Knurling machine



March25, 1952 J. J. WITTMAN 2,590,657

KNURLING MACHINE I Filed Oct. 26, 1948 INVENTOR. I JOSEPH J. WITTMAN Patented Mar. 25, 1952 sres P i The present invention in a knurling or expanding machine forkriurling fcf'expanding the inside and outside walls of an open end cylindrical object, suchfor example as a piston skirtor the like, and in'particular to such a knurlingmachine which has automatic safety means for rendering the machine inopera 'tive when excessive force is imposed on the -knurling rollers by theobjects' being knurled.

The construction of the knurling .machine of,

the present invention is particular y but not exclusively adapted to the knurlingof thef=skirts on pistons for internal combustion engines"; as more particularly set forth intheflfollowing specification.

pands the su'r-face' ofthe-piston'T skirt and permits a tightenfit of the piston skirt in 'the cylinder. Knurling of the outer surface of a piston has been fo'undtobe very desirable, since the raised portions of the knurl provide the bearing surfaces required while the grooved portions provide oil grooves on the external surface of the piston and thus assure lubrication between the piston and the cylinder walls.

relates to improvements 3 Knurling' of a pistonskirt fronrthe area below ,the'lower ring groove to the'endjof the-skirt ex- Piston knurling machines heretofore developed have been time-consuming in operation as they have utilized screw-threaded shafts and the like, for adjustably securing the pistons into knurling position under pressure. such prior devices, the knurling machine of the present invention provides a means byrwhicha piston is locked in place under spring tension by one simple movement of the locking lever.

Conventional piston expanders or knurling' machines are also'limited as to theamount of piston skirt area which they can knurlonpistons having internal bosses or reinforcing ribs. Such bosses or reinforcing ribs present obstrucing rollers used in conventional knurlingmachines or cause much breakage of the pistons if the knurling rollers are forced over such bosses or ribs.

It is, therefore, a principal ob'ject-of 'thepresent' invention to provide a knurlingmachine adapted to knurl piston skirts, which is so constructed that a piston skirt may be knurled fromthe lower As distinguished from ,40 tions which either prevent passage of the knurl-;

ring groove to the bottom of said piston skirt,- regardless of the internal construction of the said piston and in which provision is made to release the knurling pressure whenv required to eliminate breakage of the pistons.

It is a further object of the present invention machine under constant loadingofwork in the machine is accomplished with agminimum offlost-time. j

It-is ahotherzobject of thepresent invention to provide-"a knurling machine adapted to-knurl piston' skirts,'"vvhich includes an automatic, safety device whi'ch reriders the machine inoperative when an 'o'bstr'ubtidn is encounteredion said piston skirt o'r'whenthe" kn'urling rollers on said machine are subjected't'o an unduly heavy load. Itis another object of the present invention to provide a knurling machine adapted to knurl piston skirts, which can be rapidly adjusted to accommodate different sizes and types of pistons. It is a further object of the present invention to provide a knurling machine adaptedto knurl piston skirts, in which the piston isheld-inthe pressure "during the knurling operation, Q F a f" It is another object of the present invention to provide a .knurling machine adapted to knurl piston skirts, which isprovided with index markings so, arranged that each successive section ofra piston .skirtto bev knurled may; be. quickly indexed and. located, in, the proper position for eachoperation orthemachine, h j Other objects. ofthisiinventioh ,will appear in the following description' and'[appended claims, a reference beingf-ha'd to, the'accompanying drawings .forming a part of this specification whereinlike reference characters designate cor- A responding parts in the several views.

in phantom.

Fig. is a partialview oi' 'tl1e t'opotthe fixed anvil of the knurling machine shown? in Fig. 1,

i and taken. along the use in thiejdirection jofthe arrows, Fig l'." j Before explaining-the, present invention in detail, it is to be" understocd that the invention is not limited in its application to the details of construction and arrangement of partswillustrated in the accompanying drawings, since; the j invention is capable of other embodiments and of being practiced or carried out in various iways. Alsoit i s-to be understood that 'the phraseology on terminology employed herein is for the purpose of description and not of limitation.

The machine consists essentially of a fixed anvil Ill which is provided with a detachable rotatably mounted knurling roller H. Complemental plates l2 are secured by the machine bolts I3 to the fixed anvil i and extend upwardly therefrom and in spaced relation to each other to provide a. point for the pivotal attachment of the movable arm IA. The arm I4 is pivotally mounted as at I5 to the spaced plates I2 and extends outwardly and overhangs the end of the fixed anvil I0. A stop I6 is laterally disposed between the side plates I2 and is rigidly secured to the said side plates I2 by means of the bolt II. The said stop I6 limits the upward travel of the movable arm I 4. A shaft I8 is journaled in the movable member I4 and is provided with an operating crank I9 at one end and with a knurling roller 20 at its opposite end. The knurling roller 20 preferably is held in position on the shaft I8 by means of a set screw (not shown) so that said roller 20 may be rapidly removed and replaced. The knurling roller 2tl moves vertically relative to the knurling roller II and is rotatably driven by the crank I9 through the shaft I8. Vertical pivoting movement of the arm 14 relative to the pivot point I5 is controlled through the locking lever 22 which is pivotally mounted as at 23 to the forward end of the arm II. A link 24 is pivotally connected between the lever 22 and one leg of the bell crank 25 which is pivotally mounted as at 26 to the upper portion of the side members I2. The other leg of the bell crank lever 25 is connected with a clevis 21 to which is secured a screw-threaded adjusting bolt 28 which has an adjusting nut 29 mounted thereon. The nut 29 may be moved to vary the compression on the compression spring 30. The spring 30 is seated at one end on a washer 3| which is movable with the nut 29 and at the other end on a spring seat 32 which is pivotally connected as at 33 with the side portions I2 of the device. The adjusting bolt 28 extends through the spring seat 32 and adjusts the throw or amount of movement which the linkage permits in connection with the bandle 22. This adjustment is independent of the adjustment of the nut 29 for varying the compression on the spring 30.

When the operating handle 22 is moved to the position for the knurling rollers to engage a piston designated as 34 in Fig. 2, the links 24 are so arranged that the parts are only slightly beyond center. This is controlled by adjustment of the adjusting screw 35 which contacts the bell crank 25 in the operating position. Thus. when the knurling roller II strikes a projection on the inside of the piston 34 as for example a boss, reinforcing rib or the like, an upwardly directed force is exerted on the knurled roller 20 and this will trip the linkage in such a way that the roller 20 is free of compression and hence breakage of the piston is eliminated.

During the operation of the device, the roller 20 is held against the outside of the piston by a spring tension force which is exerted by the spring 30. By varying the tension on the spring 30, the force constantly exerted on the roller 20 may be varied. This construction is adequate to accommodate the ordinary variations in the thickness of piston walls and the like.

Markings 36, Fig. 3, are provided on the upper surface of the extended portion of the fixed anvil I0. The bottom of the piston skirt is placed adjacent the first of these markings-and the piston 34 is locked into place by counterclockwise movement of the locking lever 22. The crank I8 is rotated, and a section of the "piston skirt is knurled. Clockwise movement of the locking lever 22 releases the pressure on the piston 34. and the bottom of the piston skirt is moved to the second of said markings 38. This operation is repeated with the successive markings until the knurling of the piston skirt is completed. The markings 33 are so spaced that the knurled sections will slightly overlap, and no part of the piston skirt will remain unknurled.

The fixed anvil I0 is tapered near the roller II, and the roller II is of small diameter so that internal obstructions within the piston will not prevent the desired knurling on the inside of the piston skirt.

The knurling machine shown in the drawings is a vise model adapted to be gripped in a machinists vise. The said machine may also be provided as a bench type by providing suitable flanges or fastening lugs to secure the entire unit to a work bench. I

The rollers I I and 20 as shown in the drawings have the same angular position of their respective teeth. Due to the fact that the said rollers are disposed degrees apart, they rotate in opposite directions as the piston skirt is rolled between them. Thus, the knurled pattern inside the piston runs in a diiferent direction than the knurled pattern outside the piston. This reinforces and stiffens the piston walls since the knurled ribs run in opposite and crossing directions.

The knurling rollers I I and 20 may have a plain surface it the device is to be used as a piston expander and knurling is not desired. Any desired type of knurled pattern may be provided by changing rollers as required to provide the desired knurled design. Y

Having thus described my invention, I claim:

1. In a knurling machine, the combination of two complemental side plates; 2. fixed anvil disposed at the bottom of said side plates and extending forwardly therefrom; a roller rotatably and detachably secured adjacent the forward end of said fixed anvil; a movable arm pivotally attached to said side plates above said anvil and extending forwardly from said side plates; a shaft journaled in said movable arm; a roller detachably attached to the said shaft at the forward end and above the first-mentioned roller, a crank afiixed to the other end of said shaft; means for locking the cylindrical object between said rollers and resiliently holding said object in place under adjustable spring tension, said means forming an adjustable safety device which will trip when a predetermined load is exceeded on said rollers and including a locking lever pivotally secured to the forward portion of said movable arm, links pivotally connected at one end to said locking lever and at the other end to one leg of a bell crank which is pivotally attached to said side plates, a clevis pivotally attached to the other leg of said bell crank. a bolt screw-threaded to said clevis at one end and extending through a pivotal spring seat at the other end, a nut screwed onto said bolt between said clevis and said spring seat. a spring interposed between said nut and said spring seat, and surrounding said bolt, and an adjusting screw extending through said locking lever and abutting said bell crank when the looking lever is in the operative position. said adjusting screw determining the position of the locking lever in the operative position.

2. In a knurling or expanding machine adapted for knurling or expanding the inside and outside walls of a cylindrical object such as a piston skirt and which will accommodate differences in wall thicknesses of said object, the combination of tgjvo complemental side plates; a fixed anvil disposed at the bottom of said side plates and extending forwardly therefrom; a roller rotatably and .detachably secured adjacent the forward end of said fixed anvil; a movable arm pivotally attache said side plates above said anvil and exten ng forwardly from said side. plates; a shaft journal'ed in said movable arm; a roller detachably attached to the said shaft at the forward end and above the first-mentioned roller, a crank aflixed tol the other end of said shaft; and means for lockin the cylindrical object between said rollers and resiliently holding said object in place under adjustable spring tension, said last-named means comprising a locking lever pivotally securediito the forward portion of said movable arm, links pivotally connected at one end to said locking lever and at the other end to one leg of a bell crank which is pivotally attached to said side plates, a clevis pivotally attached to the other leg of said bell crank, a bolt screw-threaded to said clevis at one end and extending through a pivotal spring seat at the other end, a nut screwed onto said bolt between said clevis and said spring seat, and a spring interposed between said nut and said spring seat and surrounding said bolt.

JOSEPH J.'WITTMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 628,643 Abrahams July 11, 1899 768,771 Riegner Aug. 30, 1904 1,382,625 Clouse June 28, 1921 2,083,775 Carroll June 15, 1937 2,245,252 Cleghorn June 10, 1941 

